Biodegradable, liquid, water-miscible alkylene oxide condensation products



United States Patent 3,340,309 BIODEGRADABLE, LIQUID, WATER-MISCI- BLE ALKYLENE OXIDE CONDENSATION PRODUCTS Eugene A. Weipert, Allen Park, Mich., assignor to Wyandotte Chemicals Corporation, Wyandotte, Mich., a corporation of Michigan No Drawing. Filed June 28, 1965, Ser. No. 467,760 4 Claims. (Cl. 260-615) This invention relates to rinse additives for automatic dishwashing machines. More particularly, this invention relates to biodegradable, liquid, water-miscible alkylene oxide condensation products which are particularly useful as rinse additives for automatic dishwashing machines.

The use of rinse additives is well established both in commercial'and home automatic dishwashing machines (Soap and Chemical Specialties, 34, Feb. 1958, pp. 48-52, 170 and 171; Chemical Week, Feb. 20, 1960, pp. 89 and 90). Rinse additives result in quicker and more complete draining and drying of utensils and glassware, reduction in or freedom from so-called water spots and filming on utensils and glassware, and a brighter and cleaner appearance of all washed items. In view of the noted advantages associated with the use of rinse additives, it is clearly understandable why the use of these additives is a necessary prerequisite for obtaining satisfactory performance in automatic machine operations.

Notwithstanding this obvious need, very few products are commercially available. This may be attributed to the number of characteristics which a compound must possess in order for it to be an eifective rinse additive. These characteristics include (1) the compound must not cause or promote foaming; (2) the compound must provide good draining and drying on all items washed; (3) the compound must not leave haze or residue on utensils; (4) the compound should be effective at low concentrations, and (5) the compound should not be affected by high or low temperatures. In addition to all the above, it is now necessary that the compound be biodegradable. With such formidable requirements, it is no wonder that few compounds are effective rinse additives.

Alkylene oxide condensation products are well known in the art. Generally, they are prepared by the reaction of an organic compound having a reactive hydrogen atom with ethylene oxide, propylene oxide or higher alkylene oxides, or mixtures thereof, either added separately or jointly to the organic compound. Thus, block or heteric compounds may be and have been prepared. These compounds are well-known surface active agents which may be employed in any of several washing applications.

Now, in accordance with this invention, it has been found that a certain group of alkylene oxide condensation products possess exceptional rinse additive characteristics. The products of this invention are a cogeneric mixture of compounds having the formula:

wherein R is a straight chain alkyl group having from 8 to 20 carbon atoms, a has an average value of from 3.75 to 12.75, b has an average value of from 1.7 to 7.0, the ratio of a tob being from 1.8:1 to 22:1, from O to 10 weight percent of said compounds in said mixture having an R containing 8 carbon atoms, from O to 50 weight percent of said compounds in said mixture having an R containing 10 carbon atoms, from 0 to 95 weight percent of said compounds in said mixture having an R containing 12 carbon atoms, from 0 to 95 weight percent of said compounds in said mixture having an R containing 14 carbon atoms, from 0 to 95 weight percent of said compounds in said mixture having an R containing 16 ice carbon atoms, from O to 50 weight percent of said compounds in said mixture having an R containing 18 carbon atoms, and from 0 to 10 weight percent of said compounds in said mixture having an R containing 20 carbon atoms, the above weight percents based on a total of weight percent. The RO- in the foregoing formula may be defined as the residue of the alcohol mixture employed in the condensation reaction, i.e., the alcohol mixture with the hydrogens in the OH radicals removed.

The term cogeneric mixture, as used herein, desig nates a series of closely related homologues that are obtained by condensing a plurality of oxide units with a mixture of aliphatic alcohols. (See U.S. Patent No. 2,549,438, particularly column 2, line 40 et seq.). As is known, when a mixture of compounds of this type is generated, various oxyalkylene chain lengths are obtained.

Throughout this application when the values of a and b are referred to, average values are meant.

The alkylene oxide condensation products of this invention are prepared by condensing propylene oxide with a condensation product of ethylene oxide and a mixture of straight chain aliphatic alcohols. The products of this invention are biodegradable water-miscible liquids possessing exceptional rinse additive properties.

The crux of this invention is the finding that compounds possessing exceptional rinse additive properties can be prepared by condensing 1.70 to 7.0 moles, preferably 3.0 to 4.5 moles, of propylene oxide with a condensation product of 3.75 to 12.75 moles, preferably 5.9 to 9.0 moles, of ethylene oxide per mole of a mixture of straight chain aliphatic alcohols having from 8 to 20 carbon atoms in the aliphatic chain. The amount of propylene oxide employed will depend upon the amount of ethylene oxide employed since the ratio of ethylene oxide to propylene oxide must be maintained in a range.

of from 1.8:1 to 22:1, preferably 1.9:1 to 2.1:1. This finding may be attributed to a number of factors which are discussed herein.

The products of this invention are prepared from three components: a particular mixture of alcohols, ethylene oxide and propylene oxide, each of which plays an important part in the preparation of the rinse additives. One component employed in the preparation of the rinse additives of this invention is the alcohol mixture. Since the alcohol serves as the hydrophobic (grease removing) element of the rinse additive, it is necessary that it contain at least eight carbon atoms. However, besides containing eight carbon atoms, the alcohol must possess other properties which insure biodegradability and stability. For example, it ha been determined that no more than 10% by weight of the alcohol mixture may be an alcohol having eight carbon atoms and no more than 50% by weight of the alcohol mixture ay be an alcohol having ten carbon atoms since use of more than the stated amounts results in a product which irritates the human skin and which has an unpleasant odor. Obvi ously, neither product, regardless of its other properties, would be a satisfactory rinse additive for commercial dishwashing machines. Furthermore, it has been deter mined that no more than 50% by weight of the alcohol mixture may be an alcohol having eighteen carbon atoms and no more than 10% by weight of the alcohol mixture may be an alcohol having twenty carbon atoms since 1 the use of amounts in excess of that stated results in a product which is too hydrophobic to be useful in the chain, said mixture containing from to weight percent of an alcohol having 8 carbon atoms, 0 to 50 weight percent of an alcohol having 10 carbon atoms, 0 to 95 weight percent of an alcohol having 12 carbon atoms, 0 to 95 weight percent of an alcohol having 14 carbon atoms, 0 to 95 weight percent of an alcohol having 16 carbon atoms, 0 to 50 weight percent of an alcohol having 18 carbon atoms, and 0 to 10 Weight percent of an alcohol having 20 carbon atoms. The mixture of alcohols which is operable in this invention has an average molecular weight of from about 165 to about 265, preferably from about 180 to about 240. A preferred alcohol is commercially available under the name ALFOL 1218 which is approximately a mixture of 40% by weight C alcohol, 30% by weight C alcohol, 20% by weight C alcohol, and 10% by weight C alcohol.

Another component employed in the preparation of the products of this invention is ethylene oxide. The amount of ethylene oxide is, as are all of the variables of this invention, extremely critical. From 3.75 to 12.75 moles of ethylene oxide per mole of alcohol mixture is required to prepare the products of this invention. It has been determined that this amount of ethylene oxide is required to impart the necessary hydrophilic properties to the rinse additives. If less than 3.75 moles is employed, the resulting product is not sufliciently water-miscible to be useful in dishwashing applications, whereas if greater than 12.75 moles is employed, the resulting product foams or causes foaming in the dishwasher regardless of the amount of propylene oxide subsequently employed. As a rule of thumb which should be followed in the preparation of the products of this invention, the condensation product of the alcohol mixture and ethylene oxide should contain from 50% to 70% by weight, preferably 55% to 65% by Weight, ethylene oxide.

The third component employed in the preparation of the products of this invention is propylene oxide. Again, the amount of propylene oxide is extremely critical. From about 1.70 to 7.0 moles of propylene oxide per mole of alcohol mixture is required to prepare the products of this invention. If less than 1.70 moles of propylene oxide is employed, the resulting product is too hydrophilic and generates too much foam to be an effective rinse additive, whereas if more than 7.0 moles of propylene oxide is employed the resulting product is too hydrophobic and leaves an oily film on the washed items.

In addition to the fact that the amounts of ethylene oxide and propylene oxide are critical, it is also essential that the ethylene oxide to propylene oxide ratio be maintained between 1.8:1 to 2.211. It has been determined that products prepared with ratios less than 1.821, when subsequently employed as rinse additives, are ineffective in preventing streaking and filming of the items washed. Likewise, at ratios greater than 2.2:1, the products prepared are ineffective in preventing water spotting, especially on glasses and utensils.

The products of this invention are generally prepared in two steps. In the first step, an alcohol mixture and ethylene oxide are condensed in the presence of an alkaline condensing agent (catalyst) to form an ethoxylated product. Condensing agents which may be employed include sodium hydroxide, potassium hydroxide, sodium ethylate, sodium methylate, potassium acetate, sodium acetate, and trirnethylamine. Any other types of catalysts commonly used for alkylene oxide condensate reactions may also be employed.

' The condensation is preferably carried out at elevated temperatures and pressures. In the second step, the ethoxylated product of the first step is condensed with propylene oxide. A condensing agent, preferably potassium hydroxide, is also used in the second step which is also preferably carried out at elevated temperatures and pressures.

The following examples serve to illustrate the invention.

4 EXAMPLES I-xm Several products were prepared following the general procedure described below. Details as to the products prepared are found in Table 1.

A reaction vessel equipped with a stirrer, thermometer, inlet tube, pressure gage and heat exchange means was purged with nitrogen and charged with 0.7 part of potassium hydroxide and 214 parts of an alcohol mixture containing approximately 40% of a C alcohol, 30% of a C alcohol, 20% of a C alcohol, and 10% of a C alcohol. The charge was heated to 150 C. and pressure exerted to 30 to 40 p.s.i.g. with nitrogen.

Ethylene oxide, in the amounts stated in Table 1, was added over three to six hours at 150 C. to 160 C., maintaining the pressure under p.s.i.g. The mixture was stirred at 150 C. for one hour, then cooled to 125 C. and vented to zero pressure. Propylene oxide, in the amounts stated in Table 1, was then added at 125 C. over a two to three-hour period. The mixture was again stirred for one hour at 125 C.

The product was cooled to 75 C., neutralized with glacial acetic acid and stripped for one hour at 110 C. and at less than 10 millimeters of mercury pressure to remove volatile components. Pale yellow liquid products were obtained which were water-miscibleand biodegradable. Biodegradability was determined by the shake flask culture technique. This involves first preparing a basal medium of distilled water, yeast extract, ammonium chloride, potassium hydrogen phosphate, magnesium sulfate septahydrate, potassium chloride and ferrous sulfate and then adding a candidate surfactant (in the form of a solution) to the basal medium to give a surfactant concentration of 30 ppm. A microbial culture is prepared. based on unchlorinated final eflluent from an activated sludge plant. The basal medium containing the candidate surfactant is then inoculated with the microbial culture and placed in a shaking machine for aeration. To follow the course of biodegradation, aliquots are removed for analysis (potassium iodobismuthate method) immediately after inoculation and at 24-hour intervals thereafter for a period of seven days. The analysis indicates the amount of surfactant remaining in parts per million. Although there is uncertainty in the art as to that which is biodegradable and that which is not sufliciently biodegradable, for the purpose of this application a surfactant which degrades 85% within seven days is considered biodegradable.

The products prepared were tested as rinse additives in dishwashing machines in the following manner.

A standard detergent powder was prepared by blending the following ingredients together in a twin shell blender:

A standard soil was prepared by melting together, at a maximum temperature of F., the following ingredients in a 1000 milliliter beaker on a hotplate:

Oleomargarine (80%) 454 Starlac (powdered non-fat milk) (20%) 113.5

Total (100%) 567.5

This mixture was cooled to room temperature with occasional stirring and stored in the refrigerator prior to use.

A Hotpoint dishwasher was loaded with five glasses, three four-inch and three six-inch Melmac plates in the Parts 7 top rack and six nine-inch chinaware plates in the bottom rack, all evenly distributed. Six knives, six forks, and six teaspoons were placed in the metal holder on the lower rack. Prior to the first wash, the dishwasher was allowed to run one or two cycles, without drying, to get the machine up to temperature. The dishwasher contained no soil, detergent, rinse air or glass during this warm-up period. The test was carried out with deionized water at 135 +5 F., although a higher temperature or hard water can be used. Fifty parts of soil was weighed out on a five-inch watch glass. Two ten-part portions of standard detergent powder were weighed out into 50 milliliter beakers. On a three-inch watch glass was weighed out 0.8 part of the candidate rinse additive.

After a preliminary purge cycle, the machine went into the first wash cycle and was stopped by opening the door. The soil was placed on the bottom rack of the machine, one portion of detergent powder was added to each of the two cups provided in the door of the machine, and the door was closed. As soon as the machine went into the second rinse cycle, the door was opened and the candidate rinse additive was added to the lower rack, the door was closed and the machine completed its cycle.

After the drying cycle, the contents were cooled to room temperature and the glasses were observed in a black box for spotting or filming according to this rating:

(1) 4 spots or film (2) A-Vz spotted or filmed (3) /2 4 spotted or filmed (4) 4 spotted or filmed (5) completely spotted or filmed The higher the rating, the poorer the test results. After fifteen washing or a 5 rating, whichever came first, the test was concluded.

After rating, the glasses were returned to the dishwasher without cleaning and rotated clockwise with each other. In addition, they were also rotated turn clockwise from their original position. The ratings of the prodnets are found in Table 1. A rating of 1 or 2 is satis factory with, of course, a rating of 1 being preferred.

The product was tested according to the procedure described above and received a rating of 2. A slight amount of film was noted on the glasses.

EXAMPLE XV A product was prepared following the scribed in Example I employing:

procedure de- Parts Hydrogenated tallow alcohol (mixture of G -C alcohols, average molecular weight of 267) 267 Ethylene oxide (7.4 moles) 325 Propylene oxide (3.7 moles) 215 Ethylene oxide/propylene oxide ratio of 2.0:1.

A product was prepared following the procedure described in Example I employing:

Parts Alcohol mixture containing 2% C 65% C 26% C and 7% C alcohols, having an average molecular weight of 197 197 Ethylene oxide (10.5 moles) 462 Propylene oxide (5.25 moles) 304 Ethylene oxide/propylene oxide ratio of 2:1.

The product was tested according to the procedure described above and received a rating of 2. A slight amount of film was noted on the glasses.

EXAMPLE XVII A product was prepared following the procedure described in Example I employing:

TABLE 1 Ratio Moles Moles Ethylene Example Ethylene Propylene Oxide/ Rating Remarks Oxide Oxide Propylene Oxide 5. 9 5. 00 1.18 5 Glasses completely covered with film. 5. 9 4. 00 1. 47 5 Do. 10.8 6. 40 1. 68 4 Considerable amount of film left on glasses.

5. 9 3. 28 1. 80 2 Slight film left on glasses.

5.9 3. 10 1. 90 1 N01 film and occasional water-spot on some g asses.

8. 3 4. 0O 2. 08 1 Do.

5. 9 2. 70 2. 20 2 Slight film and water spots on glasses.

5.0 2.00 2. 50 4 Considerable amount of water spots on glasses 3. 5 1. 75 2. 00 5 Compound not water-miscible, glasses completely covered with film.

15. 0 7. 5O 2. 0O 5 Compound caused excessive foaming, glasses completely spotted and covered with film.

Examples I-XI, above, demonstrate the criticality of the ethylene oxide/propylene oxide ratio. Examples XII and XIII demonstrate the criticality of the amounts of ethylene oxide and propylene oxide.

EXAMPLE XIV A product was prepared following the procedure described in Example I employing:

Parts Alcohol derived from coconut oil (mixture of C C alcohols, average molecular weight of 211) 211 Ethylene oxide (5.94 moles) 262 Propylene oxide (3.0 moles) 174 Ethylene oxide/propylene oxide ratio of 1.98:1.

Parts Alcohol mixture containing 36% C alcohol and 64% C alcohol (average molecular weight of 176) 176 Ethylene oxide (4.73 moles) 384 Propylene oxide (2.36 moles) 137 Ethylene oxide/propylene oxide ratio of 2:1.

wherein R is a straight chain alkyl group having from 8 to 20 carbon atoms, a has an average value of 3.75 to 12.75, b has an average value of from 1.7 to 7.0, the ratio of a to b being from 1.8:1 to 22:1, from to 10 Weight percent of said compounds in said mixture having an R containing 8 carbon atoms, from O to 50 weight percent of said compounds in said mixture having an R containing 10 carbon atoms, from 0 to 95 weight percent of said compounds in said mixture having an R containing 12 carbon atoms, from 0 to 95 Weight percent of said compounds in said mixture having an R containing 14 carbon atoms, from 0 to 95 weight percent of said compounds in said mixture having an R containing 16 carbon atoms, from 0 to 50 Weight percent of said compounds in said mixture having an R containing 18 carbon atoms, and from 0 to 10 weight percent of said compounds in said mixture having an R containing 20 carbon atomsfthe above weight percents based on a total of 100' weight percent.

2. The condensation products of claim 1 when a has an average value of 5.9 to 9.0 and b has an average value 8 of from 3.0 to 4.5, the ratio of a to l being from 1.9:1 to 2.1:1.

3. The condensation productsof claim 1 when approximately 40 weight percent of said compounds in said mixture have an R containing 12 carbon atoms, weight percent of said compounds in said mixture have an R containing 14 carbon atoms, 20 Weight percent of said compounds in said mixture have an R containing 16 carbon atoms, and 10 weight percent of said compounds in said mixture have an R containing 18 carbon atoms.

4. The condensation products of claim 3 when a has an average value of from 5.9 to 9.0 and b has an average value of from 3,0 to 4.5, the ratio of a to b being from 1.9:1 to 2.1:1.

References Cited UNITED STATES PATENTS 3,030,426 4/196-2 Moseley et a1. 260-615 FOREIGN PATENTS 950,844 2/ 1964 Great Britain.

LEON ZITVER, Primary Examiner.

H. T. MARS, Assistant Examiner. 

1. BIODEGRADABLE, LIQUID, WATER-MISCIBLE CONDENSATION PRODUCTS COMPRISING A COGENERIC MIXTURE OF COMPOUNDS HAVING THE FORMULA: 